The state's top propane inspector and the lead instructor at an industry-operated school for technicians both say propane is "perfectly safe", as long as systems are installed and maintained by trained and licensed technicians.

Brian Champagne, the lead instructor at the training program operated by the Maine Energy Marketer's Association, says he heats his own home with propane and has no concerns about the basic safety of the fuel or the systems. Champagne says home and business owners should insist on having only licensed technicians work on their heating systems, and not let unlicensed people touch them. He also has a simple rule:

"If you smell propane, shut off the tank and call the company."

Champagne does advise people to make sure they protect exposed outdoors gas lines from falling ice or other hazards. He says an overhanging roof may be enough protection, but if not, a cover or guard can protect the line.

He also says gas delivery drivers will look things over when they come to the house or business, but that's no replacement for an annual service visit.

Peter Holmes of the state Fuel Board delivers a similar message. He says propane systems, even older ones, pose no danger if they're properly maintained. The Fuel Board is the state agency that licenses technicians.

Both men say the same general rules apply to both propane and natural gas systems.

Natural gas has been used in some Maine cities for decades, but it will become more widespread in the next few years as new gas pipelines are installed in several parts of the state.

Some natural gas problems can occur when exterior pipes are damaged by vehicles or construction equipment.

That happened recently at the Maine Mall, forcing the evacuation of the mall. Damage from construction equipment is also blamed for a huge fire in Kansas City, MO on Tuesday.

The experts say there are clear rules stating those pipes are supposed to be protected by some sort of barriers.